The spring equinox falls on Tuesday, March 19, marking the beginning of spring for the Northern Hemisphere
For most of the year, the Earth's axis is tilted either toward or away from the Sun
During the equinox, the Earth's axis and its orbit line up so that both hemispheres receive equal amounts of sunlight
The word equinox comes from two Latin words meaning that on the equinox, day and night are of approximately equal length
The Northern Hemisphere's vernal equinox can occur between March 19 and 21, depending on the year
The autumnal equinox can occur between September 21 and 24
According to the calendar, spring starts on March 1, summer on June 1, autumn on September 1, and winter on December 1